An electric pump can fill a tank in 2 hours. Because of a leak in the tank, it was taking 21⁄2 hours to fill the tank. The leak can drain all the water off the tank in how many hours?
In a class of 65 students there are 39 girls. The average weight of these girls is 60 Kg and average weight of the full class is 64 kgs. What is the average weight of the boys of the class?
The average marks obtained by a class of 60 students is 65. The average marks of half of the students is found to be 85. The average marks of the remaining students is
Ticket for an adult is Rs 1000 and a child is Rs 500. One child goes free with two adults. If a group has 17 adults and 5 children what is the discount the group gets?